The present invention relates to a light-sensitive sensor unit, especially for automatic switching of illuminating equipment in vehicles.
A sensor unit is discussed in German Published Patent Application No. 195 23 262, which includes a global sensor and a directional sensor by which the light conditions outside the vehicle are determined. The sensor unit is connected to the evaluation device in which, from the signals of the sensor unit, it is ascertained whether, with the actually present light conditions in the surroundings of the vehicle, a change in the switching state of the illuminating equipment is necessary. This sensor unit permits automatic switching of the illuminating equipment, but because of the global and directional technology, it includes relatively many parts, which makes for considerable costs as well as costly adjustment.
The equipment according to an exemplary embodiment of the present invention may have the advantage that, by the integration of global and directional technology, a simple, compact, robust, easy-to-install and practically adjustment-free sensor unit may be made available. In addition, the equipment may include only a minimal number of component parts, which may make possible simple and cost-effective production with broadened functionality. Since components which hinder vision may be held to a minimum on windshields of motor vehicles, the small dimensions made possible by the integration of the global and directional technology may turn out to be an additional great advantage. By the integration of the light-conducting element of the sensor unit into the light-conducting element of a rain sensor device, further component parts may be saved, and the number of visually impairing components on the windshield may be even further reduced.
Further work steps may be saved especially when the light conducting element may be manufactured by a multi-component injection molding process together with the light-conducting element of the rain sensor and the coupling medium.
Because at least three sensors may detect light from predetermined directions, a broad region in front of the vehicle may be covered.
If one sensor is positioned in the driving direction and two further sensors are positioned tilted at an angle xcex1 to each side of the driving direction, this may yield a broad detecting cone in front of the vehicle, so that tunnel entrances, which are not yet in the driving direction, may be detected, and the illuminating equipment may be appropriately controlled.
If the directional sensors have lens-like elements which may also overlap with one another, the detecting cone may be matched individually to the instructions of the vehicle manufacturer.
If the light conducting elements are integrally formed, further construction space may be saved, and the sensor unit may be further minimized.
If the sensor elements are able to distinguish between daylight and artificial light, it may be prevented that the illuminating equipment is shut off at bright illumination while driving in a tunnel.
The sensor unit according to an exemplary embodiment of the present invention may provide a substantial improvement of the response behavior of the rain sensor device, which may come about through the increase in the relationship of the sensitive surface to the contact surface, as compared to the usual rain sensors. This may be achieved by a trapeze-shaped arrangement of transmitter and receiver. Because of the oblong, coherent area, the probability may be increased that a raindrop located on the windshield will drift onto the sensitive area because of the wind generated by travel of the vehicle, which may result in an improvement of the response behavior.
By using several receivers per transmitter, the number of measured paths, and thus the number of sensitive areas may be increased, which may yield a further cost advantage.
The same effect may appear when several transmitters and only one receiver are used. If two transmitters and one receiver are used, four measured paths and thus four sensitive areas may be achieved. If the distance between the two transmitters is about twice as large as the distance between the two receivers, this may yield an especially uniform arrangement of the sensitive areas.
It may further prove advantageous to fasten the rain sensor device on the windshield in such a way that the installation position of the transmitters is on the lower parallel of the trapeze and that of the receivers on the upper parallel. Exposure to sunlight, which may preferably come from above and which may represent disturbing outside light, may thus be minimized on the receivers.
Because of the improved properties, and possibly particularly because of the improved ratio of sensitive area to contact surface, the contact surface of the sensor may be reduced, whereby the outer dimensions of the sensor on the windshield may be reduced. In this connection it may be particularly advantageous that, because of the trapeze-shaped arrangement of the transmitters and receivers, the outer dimensions of the sensor housing may nevertheless be selected to be rectangular, so that the surface area, under optimal utilization of the contact surface of the light-conducting member, may be arranged in it. A rectangular contact surface or housing additionally may have a cost-reducing effect during manufacturing. The smaller contact surface of the light-conducting member may represent an installation advantage, since with a constant contact force, the contact pressure may rise, and thereby a disturbing formation of bubbles between the coupling medium and the windshield may be avoided. In this situation it may also be possible to partially increase the surface pressure in a targeted way, by a gentle curvature of the surface, facing the windshield, of the light-conducting member at the light-entering and/or light-exiting surfaces.
It may also prove advantageous if an exemplary embodiment that in the arrangement in each case two transmitters or two receivers are positioned on the opposing parallel sides. Since, however, four measured paths, i.e. four sensitive surfaces of the sensor, may be realized each by two transmitters and two receivers, a substantial cost advantage may come about.